Design Of Distibuted Measurement System Based On Internet

With the development of the industrial technology, the testing requirements continuously improve; the test objects and test environments are increasingly complex and diverse. The traditional testing system is a stand-alone, small-scale and centralized testing system with data collection, processing and analysis on-site.The traditional testing systems cannot meet the users’needs, so the distributed measurement systems have great significance.The Shanghai GD Tek Co., Ltd develops a distributed measurement system project. In the testing environment of the implementing agencies, there are many requirements, such as test points scattered, large amount of data collection, high real-time reliability. At present, the company’s system based on the485bus has low bandwidth, real-time and scability, which is unable to meet requirements; the system based on the data acquisition card has signal transmission distance, prone to interference, high equipment costs and other shortcomings, which can’t be compatible with existing systems. As a result, the design uses the distributed mearument system.Firstly, the framework and design principles of the overall design of the distributed measurement systems are introduced. Secondly, the functions and requirements of the various parts of the system are given. Then, the design specifications of distributed data acquisition equipment are proposed. Finally, the design requirements and the principle of the selection scheme are advanced.As for the hardware design of distributed measurement system, the paper designs the host controller modules, analog input and output modules, CPLD control module, the system power supply modules, backplane modules and chassis as a whole module. The design of the main controller module is mainly on the circuit of the minimum system, RS-232serial communication module, the Ethernet interface and the LCD module. The design of the analog input and output modules is mainly on the circuit of the AD data acquisition which is composed of the AD5412, AD7192and AD7606.As for the software design of distributed measurement system, the paper designs distributed measurement system software, including PC software and distributed measurement platform software. The distributed measurement platform software includes embedded software module and CPLD control module. The paper designs the Ethernet module, data acquisition module, packet processing module, peripheral driver modules and parameter configuration module in the embedded software module; discusses the function, processes, principles, and software simulation results of the design in the CPLD control module.The last of the paper is the prototype testing, including distributed measurement platform time synchronization test, sampling rate and sampling precision test. The results verify the reasonableness of the design. Finally the paper briefly describes the design problems encountered and solutions.